DBPapers
DOI: 10.5593/SGEM2016/B13/S05.081

THE INTRAMOESIAN FAULT AS INTERPRETED ON GEOPHYSICAL, HG SPECTROMETRY AND SEISMICITY DATA

I.M. Stanciu, D.Ioane, R. Dimitriu
Tuesday 6 September 2016 by Libadmin2016

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-57-5 / ISSN 1314-2704, June 28 - July 6, 2016, Book1 Vol. 3, 639-646 pp

ABSTRACT
This study is based on an integrated interpretation of previous geological, geophysical data (gravity, magnetic, refraction and reflection seismic cross-sections), geochemical research (Hg spectrometry) and regional seismicity data, available from Romania and Bulgaria, in order to build local and regional-scale models of the Intramoesian Fault.
Since the late ‘60, the Intramoesian Fault has been described as a trans-crustal fault, extending from underneath the Carpathians, across the Moesian Platform, to the Black Sea continental shelf, its path being ambiguously located on maps.
As it does not outcrop, the geological mapping of the Intramoesian Fault was not possible, due to thick Quaternary sediments covering the Moesian Platform. Near-surface weakly consolidated sediments hide traces of faulting, while the crystalline basement has never been intercepted by wells in the vicinity of the supposed path of the Intramoesian Fault.
The integrated interpretation of airborne, ground and marine gravity and magnetic data, offer the possibility to interpret the position of the Intramoesian Fault at crustal depths, while seismic reflection and refraction data are considered to be a good constrain in advocating a “tectonic contact” of the two major compartments of the Moesian Platform along the Intramoesian Fault.
Hg spectrometry measurements carried on in Gruiu area, crossing the supposed position of the Intramoesian Fault, had as main results a group of anomalies extended on a distance of 600 m, considered to be associated with this tectonic structure.
Romplus earthquake catalogue reveals a NW-SE wide lineament of scattered epicenters in the Romanian central part of the Moesian Platform, between Mostistea and Ialomita valleys, along the direction of the Intramoesian Fault. The seismic activity here is frequent, with low magnitude earthquakes (Mw 1 – 3) occurring between 5 and 60 km depth. Higher seismic activity, related to regional active tectonics, has been observed during 1955 – 1970 and also in other two important seismogenic areas: Fagaras – Campulung region (Romania) and Shabla region (Bulgaria).
The geophysical detection of the Intramoesian Fault represents an important geotectonic goal when improving regional and crustal geophysical and geological models.

Keywords: Intramoesian Fault, Moesian Platform, geophysical data interpretation